The Microsoft 365 data loss scenarios we see most often

Most Microsoft 365 data loss is not dramatic. It is quiet, accidental and often discovered too late.

When organisations think about losing data, they often picture a major cyber incident or headline-grabbing outage. In reality, the situations that cause the most disruption are far more ordinary. A click made in good faith. A cleanup task that went too far. A setting changed without fully understanding the impact.

Below are the most common Microsoft 365 data loss scenarios we see in UK organisations, and why backup matters in each case.

1. Accidental deletion that goes unnoticed

This is by far the most common scenario.

A user deletes:

• A SharePoint folder
• A Teams channel
• A OneDrive directory
• An email folder they believe is no longer needed

No one notices immediately. Days or weeks later, someone needs that data.

By this point:

• The recycle bin has been emptied
• Retention has expired
• Version history is no longer available

Without a backup, recovery becomes impossible or relies on incomplete workarounds.

Why backup matters

A proper backup allows you to restore the data exactly as it was, even weeks after the original deletion, without impacting current content.

2. Overwrites and ‘helpful’ clean-ups

Not all data loss looks like deletion.

We regularly see situations where:

• Files are overwritten with incorrect versions
• Folder structures are reorganised incorrectly
• SharePoint sites are “tidied” without understanding dependencies
• Teams files are moved or renamed, breaking links and workflows

Because the data still exists, these issues are often dismissed as minor. In practice, they can be extremely disruptive.

Why backup matters‍

Point-in-time restore lets you recover the correct version without rolling back everything else that has changed since.

3. Departing employees and lost OneDrive data

When an employee leaves, their Microsoft 365 account is usually disabled or removed after a set period.

If OneDrive content has not been:

• Reviewed
• Transferred
• Explicitly retained

…it may be permanently deleted once the account is removed.

This is often discovered months later when a project needs historical files or emails.

Why backup matters
Backup preserves user data independently of account lifecycle decisions, removing pressure from offboarding timelines.

4. Teams channel and chat loss

Microsoft Teams creates data in multiple places:

• SharePoint for files
• Exchange for chat messages
• OneDrive for private channel content

When a Team or channel is deleted, that data can be fragmented or lost entirely depending on configuration and timing.

Why backup matters
A unified Microsoft 365 backup captures Teams data consistently and allows granular restores of chats, files or entire channels.

5. Ransomware and mass file corruption

While Microsoft provides strong platform security, ransomware increasingly targets synced endpoints and cloud-connected data.

Common patterns include:

• Encrypted files syncing back to OneDrive or SharePoint
• Malicious bulk changes spreading rapidly
• Clean versions overwritten before detection

Once corrupted data has replicated, recovery options are limited.

Why backup matters
Isolated, immutable backups allow you to restore clean data from before the attack, without reintroducing infected files.

6. Misconfiguration and automation mistakes

Power Automate flows, third-party integrations and admin changes can all cause unexpected data impact.

Examples include:

• Automated deletions running incorrectly
• Retention policies applied too broadly
• App permissions removing or modifying content at scale

These issues often affect large volumes of data very quickly.

Why backup matters
Backup provides a safety net when automation behaves in ways you did not anticipate.

These are not edge cases

None of these scenarios require:

• A sophisticated attacker
• A platform outage
• A major technical failure

They are normal outcomes of human behaviour, change and complexity.

Microsoft 365 is a powerful platform, but power without recovery creates risk. Backup exists to absorb that risk quietly, without drama.

A simple test to try this week

Ask yourself - If this happened today, could we restore the data quickly and confidently?

Pick one scenario above and walk through your recovery process end to end. The gaps usually become clear very quickly.